I am finally getting around to trying to tune my new engine. I am having a recurring problem that has pretty much always been happening with this car since I bought it. I need a little to insight as to what direction to head for troubleshooting.
Current combination is stock block 342, trick flow 190 fac heads, track heat intake, Comp XE276HR-12, 1.7 rockers, shorty headers, 39lb injectors, 80mm stock 96 mustang MAF, 70mm throttle body and 75mm elbow, aluminum flywheel.

Like I said, the car has done this off and on since I owned it, with different injectors and MAF meters. I had the injector harness apart to change the plugs to the EV6 style. While unwrapped I did inspect for damage and issues. I have pulled codes and only get the one for having a chip/tuner. O2 sensors have been replaced in the past as part of searching for the problem, and also just because they were so old. TPS shows smooth linear voltage, IAC has been swapped with a couple different Ford ones, distributor was replaced with a known good Ford unit, TFI module was also replaced with a known working Ford unit. I have also dressed up all grounds. I am starting to suspect a harness issue or ECM problem.

I dont have any logs, but it has on occasion, just died and was very very difficult to restart. It would pop and sputter and took alot of throttle work to get it going. Once running it would bellow out blackish smoke, pop, sputter, and finally clear up. Once cleared up, it was fine as long as it was moving. Then like magic, problem goes away for several days to weeks before reoccurring.

The car will idle fine at times with no issues. Other times, when coming to a stop, or after revving the engine, it will settle to a good idle, and just die. Basically like you turned the key off. I just started pulling datalogs to try to see whatss happening. The biggest thing I have noticed is my lambse1 and 2 go from 14ish to 10ish right before it dies and also the pw1 and 2 shoot up from low 1s to mid 10s when this happens. I am trying to learn this as I go, but work keeps getting in the way. I am attaching a data log that shows whats going on. I just out the cruising portions to help scale it down. I can also cut down on the things logged to help out.

Any and all help is greatly appreciated.

Weird. The injector PWs are all over the place. Could you post the tune?

_________________
1993 Mustang LX, R331, Ported Trick Flow Heads, Holley Systemax, Custom Camshaft, Tremec 3550, 30# injectors, Pro-M 80mm MAF, A9L, Quarterhorse, BE/EA, Innovate MTX-L

Arrrgggggg. I just had a really long reply disappear. So anyways, yes, I can post my tune tomorrow. However I have had this problem with even the factory tune and hardware. It does not change whether I am at 75 ect or 230 ect. It will just appear out the blue and disappear out the blue. Today it appeared heavily after my initial post, but then disappeared...

Here is the tune I am currently running. It has done this with stock tune, cobra tune, stock tune with 24lb injector settings, etc.

step 1 when diagnosing intermittent power issues is to replace the ecu and fp relay, then upgade the gounds to the ecu and chassis

I have considered the relays, but forgot to mention this is a 95. So I either have to solder new ones in place, or replace the ccrm. Is it possible for a relay to cause issues intermittently? I was under the impression they either work or didn't.

I was watching the dashboard in be yesterday and noticed when coming to a stop is the biggest problem area. Almost stopped but not quite, it will idle fine(as in 1mph). Once at a complete stop, the idle will settle in to 800 or so, then jump to 1200 and die. When restarted, the lambses are in the 8-10 range, left hego will be at max and right hego at min but neither switching, and pw is 10ish. I can hold the throttle to 1500-2000 for about 30secs or so then all of a sudden left hego(sometimes both) starts switching and lambses go back to the 14ish range, pw drops back to 1-2ish and car will idle rock solid. However, at other times, it will idle with no issues. When I say at other times, I am talking minutes apart. Might idle great 5 stops in a row, then act up the next 3, then go back to idling good the next few.

whoa that doesn't sound right at all, almost sounds like you got a rich decel and an intermittent power loss


force open loop below 10 load or so using fn338 be sure lolodh isn't 0, a value of 3 works well

next be sure the power isn't dropping out causing it to conk, log the vbat and make sure it doesn't drop below 12.5v, if it does go drop up the keypower scaling scalar (10v should do) and increase the constant (.5 sec should do)

what does your ipsibr and isckam look like at stable idle? whats your warm idle iscdc?

if lambses are demanding 8-10 on startup with a warm engine you need to fix that asap, the richest any engine is going to want is 12.5 on a hot startup

have you tried the cbaza base tune? that would rule out any tune related errors although you said it did it on the stock tune as well

I will have to run another log after work to get the isckam. The ipsibr goes to a max of .4 on occasion, but mostly runs at 0. Battery voltage stays around 13.1-4 while running, 12.4 or so engine off, and drops to about 10 on occasion while cranking.

I will probably work on a new tune using the basic cbaza strategy and tm40 calibration included with BE just for kicks. It also will help me locate things like you are referring to, as they are labeled different in Adam's strategy.

I may pull the ecm this weekend and crack it open and also see if I cant take a look at the ecm harness. The ccrm has been opened recently, and is suspect looking at the circuit board. If the fuel pump relay or ecm relay was cutting out, what should I look for in a datalog?

fn338 I can not locate this one

lolodh is currently set to 0, but has a max setting of 2

ISCDC ranges from .4 to .6

What is another name for keypower scaling scalar?

Dechipha? Where did you go? Trying to answer your questions to work on my issues